1. Field Of The Invention
The invention relates to a mold release composition. The invention also relates to a method of producing molded ceramic articles. The invention particularly relates to mold release compositions which generate low amounts of smoke in the production of molded ceramic articles.
2. Description Of Other Related Methods In The Field
It is well-known to use a mold release agent natural or synthetic compounds such as silicone oil, mineral oils, waxes, aliphatic acid derivatives, glycols or inorganic materials such as tale or mica to produce molded articles such as polymeric materials, cement and ceramics. The mold release agent is typically applied to the mold pattern surface prior to introducing the molding composition to the mold. The molded article is then demolded and optionally dried and/or baked to achieve the final properties of the molded ceramic article. In demolding, amounts of mold release agent transfer to the molded article. In particular, mineral oil base mold release agents transfer to the molded article in relatively large amounts. In the drying or baking steps these mineral oils decompose with the evolution of smoke. Amounts of smoke may adhere to the ceramic article diminishing the uniformity of appearance of the final product. There is a need in the art for an oil base mold release agent with reduced smoke producing characteristics.
U.S. Pat. No. 4,886,838 to J. E. Dewhurst teaches an internal mold release agent for use in reaction injection molding. The mold release agent comprises compounds based on C.sub.8 to C.sub.24 fatty acids including tall oil fatty acids and oleic acid.
U.S. Pat. No. 4,740,324 to H. Schur teaches an oil base mold release agent. Preferred oils include rape seed oil and soya oil. Tall resin obtained by fractional distillation of tall oil is incorporated into the composition. Lubricating oil is also included.
U.S. Pat. No. 4,071,368 to J. R. Jones teaches petroleum distillate fractions such as kerosene in mold release compositions and the undesirability of compositions which produce smoke.